Overload-circuit breaker



Nov 27,1923 1,475,166

c. R. BEALL ET AL OVERLOAD CIRCUIT BREAKER Filed Ndv. 12. 1919 Vie/LL ATTOR EY Patented Nov. 27, 1923.

UNITED STATES PATENT OFFICE.

CHARLES B. BEALL, OFSWISSVALE,

SYLVANIA, ASSIGNORS TO THE AND ROBERT M. GIL SON, O1 PITTSBURGH, PENN- UNION SWITCH & SIGNAL COMPANY VALE, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA OI' SWISS- OVERLOAD-CIRCUIT BREAKER.

Application filed November 12, 1919. Serial in. 337,449.

To all whom it may concern:

Be it known that we, CHARLES R. BEALL and ROBERT M. GILSON, citizens of the United States, residing at Swissvale and Pittsburgh, respectively, in the county of Allegheny and State of Pennsylvania, have invented certain new and useful Improvements in Overload-Circuit Breakers, of which the following is a specification.

Our invention relates to overload circuitbreakers, and particularly to circuit breakers designed for operation by a prolonged, cur-.

. rent above a given value but not by a'imomentary surge of current above such value.

One object of 'our invention is the provision of a circuit breaker of this character which is simple and inexpensive to construct,

yet reliable in operation.

- We will describe two forms of circuit breakers embodying our invention, and will then point out the novel features thereof in claims.

In the accompanying drawing, Fig. 1 is a view showing one form of circuit breaker embodying our invention, and Fig. 2 is a -view showing a modified form of circuit breaker also embodying our invention.

Similar reference characters refer to similar parts in each of the views.

Referring first to Fig. 1, the reference character 1 designates a core member having a pole-piece 1 at the -lower end. Attached to the upper end of this core is one of an L-shaped member'2 the other leg le 0? which is parallel to the core and terminates'near thepoleiece 1. An armature' 3 is pivotally attac edto the lower end of the member 2 and is movable towards and away from the pole-piece 1. The parts thus far referred to are of magnetizable material, usually soft iron, and it will be seen that they constitute a magnetic circuit having an air ap which ismaximum or minimum accor ing as armature 3 is'open or closed. This armature is biased to the open position, and is, of course, closed when mag netic flux of su'fiicient density flows there through.

'Mounted on the core 1 is a winding 4 for creating ma etic flux in the circuit just referredtq. etween the winding and the core is a'slee've'ti of electroconductive material, such aseopper, the purpose of which is to delay the uilding up of flux in the maging 4, contact parts of winding 4, which collar'is spaced from member 2 by an air gap 7. In order to force a large proportion of the total fluxthrough the shunt path during a momentary surge of current in winding-4, 8. band 8 of electroconductive material is placed on the core 1 between the pole-piece 1' and the collar 6.

This band 8' and the sleeve 5, of course, have no effect on the flux created in the-magnetic circuit by'a current ofconstantvvalue' in winding 4. p

The operationof the elements thus far referred to is as follows: As long as current of a definite value or less flows in winding- 4 the armature 3 will remain open, but when a steady currentof greater value is supplied to the winding the armature will. close,

Vhen, however, the. winding carries a momentary surge of current above such definite value, the s eeve 5 will delay the building up of flux, and the-band 8 will force the greater part of the increasin flux through the shunt path 6, 7, so that t e flux density in 'armature.'3"will.be insuflicient to cause the latter to close. The" surge of current 'will, therefore, have no efl'e'ctgon the device.

The. circuit controlling portion of the device comprises a fixed-contact member 9 and a contact spring 10 which normally tends to move away from provided with a handle 12-by which itmay be. moved into enga ement with the member 9, and it is normal y.

connected with thesprin 10 at 11, and is provided with a should er 11" which coacts with a hook 13 attached to a fixed block 14. When'. '.armature 3 closes, a toe 15 carried by the armature. raises latch 11 and so contact opens. It may be closed by means of handle 12. As here shown, the circuit breaker is included'in circuit with a motor and a battery, the circuit being frombattery 16, through, motor 17, contact 19, wind- 9-10 to battery 16. The the circuit breaker are 50 adjusted member 9. Spring 10 is held in the latter po- .sition by alatcli 11. This latch is pivotally releases the latter from hook 13 so that the that the normal operating current taken by motor 17 will not cause the breaker to open,

but that a prolonged current above this value, such as will occur if the motor becomes stalled, will cause the breaker toopen and so avoid injury to the apparatus. The current drawn-by the motor while starting is, of course, in excess of the normal operating current, but this excess is merely a momenta-ry surge which for reasonspointed out hereinbefore, has no effect on armature 3 and so does not cause the circuit breaker to open.

Referring now to 'Fig. 2, the breaker in the form here shown comprises, as before, a core 1 surrounded by a copper sleeve 5 and provided with a winding 4. Attached to the pole-piece l the pivotal point being left-hand section of the armature.

to the right of the'middle point of the armature so that' the armature is biased to the position shown whereinit is separated from leg 22 by a block 20 of non-magnetizable material.

It will be seen that this structure two paths in multiple for the flu); in core 1, one path being through leg 22 and the right hand portion of armature 3, and the other path being. through leg 22 and the Then the armature'is in the position shown, the air gap between the armature and leg 22 is greater than that between the armature and leg '22", so that the reluctance of the right hand path is greater than that of the left hand path; consequently, when a steady current of a given value flows in winding 4 the armature will close, that is, it will swing in clockwise direction from the position shown. Leg 22" is surrounded by a copper sleeve 21, so that most of the varying flux due to a momentary surge of current above the given value in winding 4 will be forced through leg 22 and, so will have no effect on armature 3. The building up of flux due to a surge of current is also delayed by-a copper sleeve 5 as in Fig. 1. The operation of the device will be apparent from the foregoing explanation of the device shown in Fig. 1.

The control of contact 910 by the armature in Fig. 2 is the same as in Fig. 1.

Although we have herein shown and described only two forms of circuit breaker em: bodying our mvention, it is understood that various changes and modifications may be made therein within 'the scope of the appended claims without departing 'from the spirit and scope of our invention.

Having thusdescribed our invention, what we claim is:.'

1. An overload circuit breaker comprisbranch provides ing a" magnet,a normally open armature associated therewith. a contact controlled by saidarmature, a magnetic shunt around said-armature, and means for causing the greater part of the flux'due to a varying .value because of. said shunt and the means for forcing varying flux therethrough.

2. A circuit breaker comprising a mag netic circuit having an air gap, and a member. biased to a position wherein said air gap is maximum and movable'to a position wherein said air gap is minimum, a winding forcreat" ing flux in said magnetic circuit, a branch path around said air gap, a band of electroconductivemat'erial around a portion ofsaid magnetic circuit for -forcing the majority of a-warying fluxjto pass through said ath instead of through said air gap, an n a contact controlled by said movable merhben; v

A circuitlbreaken comprising a magnetic circuit having an air gap, and a mem ber biased to a position wherein said air gap is maximum and movable to a position wherein said air gap is minimum, a winding for creating flux in saidmagnetic' circuit, a;

branch path around said air gap, means asso-' p, and a contact conminimum, a winding for creating flux in both of said paths, means for forcing the greater part of a varying magnetic flux through the other of 'said paths, a' normally closed contact, and means for opening said contact when said member moves to its minimum air gap position.

5. A circuit breaker comprising a magnetic circuit havin two paths in multiple, one of saidpaths including an air gap and a movable member biased to a position wherein said air gap is maximum and movable to a position wherein the air gap is minimum, a winding for creating flux in both of said aths, a band of electro-conductive material around a portion of said one path 'for forcing the majority of a varying flux through the other path, and a contact controlled by said movable member.

movable member biased to a position wherein said air gap is maximum and movable to a position wherein the air, gap is minimum, a winding for creating flux in both of said paths, means for forcing-part of a varyingmagnetic flux through said other path, means for delaying the building up of magnetic flux in saidcircuit due to a current of increasing yalue in said winding, and a contact controlled by said movable member.

7 A. circuit breaker comprising a "magnetic circuit having an air gap and amovable member biased to a position wherein said air gap is maximum and movable to a position wherein the air gap is minimum, a winding for creating flux in said magnetic circuit, means for delaying the increase of flux in said magnetic circuit due to an increasing current msaid winding, and a contact controlled by said movable member.

8. A circuit breaker comprising a magnet, an armature controlled. thereby, a branch path of considerable reluctance for shunting part of the magnetic flux created by said magnet away from said armature, means for causing the greater part of a varying magnetic flux in said magnet to traverse said branch trolled by said armature.

9. A circuit breaker comprising a core, a winding thereon, a strap of ma netizable material extending from one en of said core to a location adjacent the other end. an armature pivotally attached to said strap and movable towards and away from the latter end of said core, a member of n'iagnetizable material extending towardssaid strap from a pdint on said core at a point between said winding and the latter end of the core, a band of electroconductive material around the core between said point and the latter end of the core, and a contact controlled by said armature.

10. A circuit breaker comprising a magnetic circuit havingtwo paths in multiple, one of said paths including an air gap and path, and a contact con-' a movable member biased to a position,

wherein said air gap is maximum and mov-. able to a position wherein the air gap is minimum, a winding for creating flux in both of said paths, means associated with said magnetic 'circuit for causing the greater part of a varying magnetic flux to pass through the other of said paths, a normally closed contact included in circuit with said winding, and means controlled by said movable member for opening said contact when the member move to such position that the 7 air ga isminimum.

11. circuit breaker com rising a magnetic circuit having two pat s in multiple,

one of said paths including an air gap and a movable member biased to a position wherein said air gap is maximum and movable to a position wherein the air gap is minimum, a winding for creating flux in both' of said paths, means associated with said magentic circuit for causing the greater part of a varying magnetic flux to pass through the other of said paths, a contact biased to the open position, means for latching said contact in the closed position, and

CHARLES R. BEALL. ROBERT M. GILSON.

Witnesses A. HERMANN WEGNER, E. P. CRUM. 

